It is hard to find a decent road bike under $300 new. Entry level seems to be around $700 retail at a LBS. If you want to chance buying online, you can probably find something decent for $600 or so, but if I were you, I would look for a sale and buy something locally. I know it isn't what you want to hear, but road bikes aren't cheap. At the $300 price point, maybe best to look into something used.